We now investigate the pump frequency dependence of the light-enhanced entanglement. As shown in Fig. REF (b), the light-induced changes are weak for \(\Omega < 10 t_h\) . Since the particle-hole excitations in our EHM cost \(U-2V=10t_h\) , low-frequency pump pulses do not have enough energy to create doublon-hole pairs and scramble the spin configurations. Thus, the transient increase of \(f_Q\) , which disappears when the pump is over, can be attributed to the Floquet engineering of the spin exchange interaction through virtual processes [1]}. The maximal enhancement is achieved for \(\Omega \sim 10 - 11t_h\) , resonant to the doublon-holon excitation energy. In this case, long-wavelength spin fluctuations are generated through the creation and annihilation of doublon-hole pairs, which contribute to a more entangled many-body state. This process is slightly reduced when the pump photon energy is higher than the doublon-holon excitation energy.
